Add depends and repo infomation to auto-generated elpa recipes.

Add depends and repo infomation to auto-generated elpa recipes.

`elpa/auto-complete.rcp` for example.
Previous:
```lisp
(:name auto-complete
:auto-generated t
:type elpa
:description "Auto Completion for GNU Emacs [source: github]")
```
Now:
```lisp
(:name auto-complete
:auto-generated t
:type elpa
:description "Auto Completion for GNU Emacs [source: github]"
:repo ("melpa" . "http://melpa.milkbox.net/packages/")
:depends (popup)
)
```